Typically, an image-forming device such as a copying machine or a printer includes the function of stapling sheets of paper and the function of arranging and stacking the sheets of paper on a stacker tray in the paper post-processing processes that discharge the paper from the paper discharge to the stacker tray.
In the conventional paper stacking device in the paper post-processing, disclosed is a roller structure movable in the vertical direction so as to move the paper to the stacker tray. This is a structure to enable the paper transferred after lowering the roller to move by pressing the paper toward the stacker tray.
In such a structure, there is a possibility that the paper is removed or pressed in the process of moving the paper by the rotation and the friction force of the roller. In addition, sheets of paper are sometimes not easily arranged in the process of moving the paper to the roller above the stacker tray, and the sheets of the paper are sometimes not arranged by the friction between the sheets of the paper in the process of the paper dropping on the stacker tray.
Thus, there is a problem that the operator must arrange the paper again after the paper is stacked on the stacker tray, and therefore the present applicant has proposed a paper post-processing device that makes it possible to grip several sheets of the arranged paper after stacking and arranging the paper temporarily on the paper stacking plate, and to transfer the paper to the stacker tray to stack so as not to fold and bend the paper (Patent Literature 1).